Total and Free Ionic Fluoride in Human and Cow’s Milk as Determined by Gas-Liquid Chromatography and the Fluoride Electrode

Abstract

The fluorine concentration in human milk from areas where the drinking water has been fluoridated for the last 18 years and in areas without artificial water fluoridation was determined by gas-liquid chromatography (GLC) and by fluoride electrode. Two fractions could be distinguished in milk: a free ionic fluoride measurable with the electrode and a non-free fluorine fraction. Probably at least 80% of this non-free fluorine fraction is in ionic form, and is thus fluoride as well. The mean total fluorine values (GLC) of 10 and 9 mothers from the low and the high fluoride areas, respectively, were not significantly different (0.046 and 0.052 ppm); the free ionic fluoride (measured at pH 4.7) was 0.004 and 0.008 ppm, respectively. Cow’s milk had a mean total fluorine value of 0.103 ppm (GLC) of which 16% was measurable with the electrode. Three cows grazing in pastures contaminated with fluoride from an industrial effluent (intake 0.4–2 mg/kg weight) yielded a mean total fluorine concentration in milk of 0.283 ppm. About 50% was measurable with the electrode.